linux-kernel - Re: [PATCH] soc: rockchip: power-domain: remove PM clocks

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Date:   Thu, 1 Mar 2018 12:54:46 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     JeffyChen <jeffy.chen@...k-chips.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Robin Murphy <robin.murphy@....com>,
        Heiko Stuebner <heiko@...ech.de>,
        Caesar Wang <wxt@...k-chips.com>,
        Elaine Zhang <zhangqing@...k-chips.com>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] soc: rockchip: power-domain: remove PM clocks

Hi Ulf,

On Thu, Mar 1, 2018 at 12:22 PM, Ulf Hansson <ulf.hansson@...aro.org> wrote:
> On 1 March 2018 at 11:37, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>> On Thu, Mar 1, 2018 at 11:18 AM, Ulf Hansson <ulf.hansson@...aro.org> wrote:
>>> Another problem with the PM clk is, more exactly with
>>> pm_clk_suspend|resume(), that those invokes only clk_enable|disable().
>>> pm_clk_suspend|resume() can't call clk_prepare|unprepare(), because we
>>> don't know if we running in atomic context when those are executed.
>>> Potentially this means leaving the clocks ungated - all the time.
>>>
>>> I have though about how to fix the above, several times, but I always
>>> ends up with thinking that's it more easy, to let the driver deal with
>>> the clocks, as then the problem goes away.
>>
>> There's a similar issue with powering on/off power areas.
>
> I don't follow. Can you elaborate?

I intended to comment on the atomic context (or not).
But I think I was wrong, and PM domain drivers do busy loops instead
of sleeps.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds